Rotary displacement device



March 1951 c. BANCROFT 2,544,480

ROTARY DISPLACEMENT DEVICE Filed Jan. 13, 1945 6 Sheets-Sheet 1 IN V EN TOR. Char/e5 Bancroff ATTORNEY March 6, 1951 c. BANCROFT ROTARY DISPLACEMENT DEVICE 6 Sheets-Sheet 2 Filed Jan. 13, 1945 INVENTOR- Char/es Earn- March 6, 1951 c. BANCROFT 2,544,480

ROTARY DISPLACEMENT DEVICE Filed Jan. 13, 1945 6 Sheets-Sheet 3 INVEN TOR.

i Char/es Bane/a f7 ,4 TTORNE Y March 6, 1951 c. BANCROFT 2,544,480

ROTARY DISPLACEMENT DEVICE Filed Jan. 15, 1945 6 Sheets-Sheet 4 INVENTOR. Char/es Eantfo f7 ATTORNE Y March 6, 1951 c. BANCROFT ROTARY DISPLACEMENT DEVICE Filed Jan. 15, 1945 6 Sheets-Sheet 5 ATTORNEY v March 6, 1951 Filed Jan. 15, 1945 C. BANCROFT ROTARY DISPLACEMENT DEVICE 6 Sheets-Sheet 6 INVENTOR. Char/es Bans-raff- ATTORNEY i atenteci Mar. 6, 195i UNITED STATES PATENT OFFICE 2,544,480 ROTARY DISPLACEMENT DEVICE Charles Bancroft, New Canaan, Conn. Application January is, 1945, Serial Nd. 572,611 2 claims. (or. 103-429) This invention relates to rotary displacement devices of the alternately accelerating piston type such as are disclosed in my prior Patents 2,132,596 and 2,270,493. In these patent-s1 have disclosed rotary displacement devices of the alternately accelerating piston type wherein the fluids are handled in a chamber having walls movable with the working vane pistons. Thus I avoid using the common and well knoW-ncombination of a piston moving in a stationary chamber of large area. So far as I am aware, it has not been possible heretofore to construct such rotary displacementdevices with more than two vane pistons in each set of pistons. Whilea device so constructed will operate satisfactorily, the loss due to friction between the several moving parts is considerable. In accordance with the present invention, I provide a simplerotary displacement device in which three or more vane pistons on each set of pistons can be utilized. This enables the useful work to be increased in a unit of given size and makes possible the bal ancing of fluid pressures found at given points in the device so that loads on pistonbeari-ngs can be cancelled out and friction and wear reduced.

The rotary displacement device of the present invention also utilizes a multiple throw crankshaft, in cooperation with multiple members con necting the piston sets, whereby crankshaft bearing pressures resulting fr-om,mechanical torque conversion are reduced and rotation of theQpi ton sets is mechanically controlled from more than one point so that the greater part of the loads on piston bearings resulting from mechanical torque isalso balanced out. I I I By utilizing more than two vane pistons'ineach piston set I am alsoab'le to reduce ;the rate of movement of the several piston sets relative to the crankshaft by providing means controlling rotation of the members connecting the piston sets, in their rotation on the crankpin so that while a given connecting member makes, one revolution in one direction with respect to the stator, the crankshaft completes as many revolutions, with respect to the given connecting vmember,in the opposite direction, as there are individual vane pistons on each set of pistons. For example, if each piston set includes four vane pistons, then the crankshaft will complete four revolutions relative to the connecting member in adirection opposite to that of rotation of the connecting member during each rotation of the connecting member. Stated otherwise, for=each-revolution .of the connecting member with respect'to the stator in one direction, the crankshaft-rotates that number of revolutions with respect to the stator in an opposite direction whichis equal to the number of vane pistons iri each set of pistons minus one.

Inasmuch as the rotary displacement device of the present invention includes multiple piston sets, having .a multiple number of vane pistons which are alternately accelerated, it is possible to utilize the device as an internal combustion engine, admitting fuel at one .or more points in the travel of the pistons, firing the admitted charge or charges, and subsequently scavenging the explodedcharge or charges after useful work has been performed. Thus, a single device may include one or more fuel admission means, one or more firing means, and one or more scavenging means, positioned about the periphery of the device. In one form of the device which is presently disclosed, two" separate power impulses are imparted to each vane piston during one complete revolution of the piston in the casing. It should be readily apparent that in such a device one can oppose various pressures so that, in effect, they neutralize each other. This simplifies construction, operation. and maintenance.

In another modified form of the device of the present invention,it is possible to generate power in the deviceand to use simultaneously in the same device the generatedpower to draw in, compressand eject a fluid. Thus, it is possible in a single stator to generate power used for the pumping or compressing of a fluid in the same stator. In the case of gas compression, the heat in the exhaust gases fromthe internal combustion engine portion of the rotary displacement device can be utilized to heat the compressed gas and so impart additionalenergy to that gas. In addition, and .as will presently appear further in detail, the compressed gas which is not completely scavenged from the device is utilized :to improve the efficiency of operation of the device.

further d'i-lficu'lty which I have observed in the operation of rotary displacement devices including movable walls and piston setsis that of providing an adequate seal about. these: same parts. I have found that this can be simply and feasibly cared for by bleeding fluid under pressure from the piston channel and applying the pressure provided by. the bled fluid against those members providing the piston forming channel. The pressures found within the piston channel are thus substantially neutralized onthe opposite side, the member forming the piston channels being pressed against the pistons and so maintained in position that a positive seal of the channel is effected.

It is in general the broad object to provide an improved rotary displacement device.

A further object of the present invention is to provide a, rotary displacement device in which multiple sets of pistons having multiple vane pistons are utilized in conjunction with a multiple throw crankshaft so that various bearing pressures, stresses, etc, are considerably reduced or are neutralized in the device whereby the construction, operation and maintenance of the device is improved and simplified.

A further object of the present invention is to provide a rotary displacement device which is capable of simultaneous use as an internal combustion engine and a fluid pump or compressor.

A further object of the present invention is to provide a rotary displacement device having multiple vane pistons movable in a piston channel which is maintained substantially fluid-tight by pressure applied on the walls opposite to the channel and supplied by fluid bled or allowed to leak from some point in the piston channel or supplied from an external source.

The invention includes other objects, novel features and advantages, some of which, together with the foregoing, will appear hereinafter wherein the present preferred form of rotary displacement device of this invention is disclosed.

In the drawings accompanying and forming a part hereof,

Figure 1 is a longitudinal section through a rotary displacement device embodying the present invention.

Figure 2 is a partial transverse section with portions of the device cut away to illustrate certain features of the internal construction of the device but with the crankshaft turned 45 degrees from the position shown in Figure 1.

Figure 3 is a longitudinal section illustrating construction of one of the several piston sets employed.

Fig. 4 is a side elevation of the construction shown by Fig. 3.

Figure 5 is an isometric view illustrating the construction of a connecting member.

Figure 6 is a side elevation partly in section illustrating construction of a device operated entirely as an internal combustion engine.

Figure '7 is a schematic sketch illustrating utilization of a device embodying the present invention as a combined internal combustion engine and an air compressor with the compressed air employed to drive a turbine wheel to produce rotary torque, the device being shown in conjunction with other apparatus whereby heat of the exhaust is used to add additional energy to the compressed air.

Figure 8 is a transverse section partly in elevation illustrating a device adapted to be employed as an internal combustion engine and an air compressor.

Figure 9 is an exploded isometric view of the principal driving members and the piston sets.

Referring particularly to the form of device shown in Figures 1-4, a stator, generally indicated at H, is provided. The stator is generally held against rotation by a suitable base or other means. It is made up of three main elements, a central section l2 and two like end sections or end bells I3, the central section and each of the end sections having ears I4 joined together by bolts l6. Each of the end bells and the central sections are cored out as at I! and are con-- nected by passages l8 to permit the circulation through the stator of a cooling fluid admitted through inlet 94 and withdrawn through outlet 96. Caps 8! are secured to each end bell by studs 68, the caps supporting crankshaft 66 for rota-- tion.

In the form of the device illustrated, severalpiston sets are provided, two of which are iden-- tical. Numeral 2| is applied to each of these and in Figure 3 I have illustrated the piston set 2| which appears on the left hand side of Figure 1.- Each piston set 2| includes four vane pistons- 22 thereon joined to one side of a wall 23. A plurality of circular fins 24 extend from the other side of the wall to assist in transfer of heat to the end bells which are provided with similar fins cooperatively positioned.

Wall 23 on each piston set 2| is formed with an inner circular flange or annular member 29 which extends on both sides of the wall. On one side of member 29 a plurality of labyrinth grooves 44 are formed to provide a seal between each piston set 2| and a third, presently described piston set 5|. To provide for rotational support of each piston set 2|, the other side of member 29 is engaged with a removable bearing support member 33 having a bearing 34 formed thereon. This bearing is engaged with a bearing 36 (Figure 1) on a presently described ring gear member 39 which is secured by studs 4| to each end bell l3. The bearing support member 33 is removable to enable connecting members 6| and 62 to be inserted and engaged with each piston set 2| and piston set 5|. This engagement is accomplished by providing crankpins 26 and 2'! on each piston set 2|, the pins being apart and extending in opposite directions from a wall portion 28 (Figures 2, 3 and 9) formed on one side of annular member 29. Each wall 28 is slotted as at 40 to permit the crankpin 26 from one piston set 2| to pass and as at 35 to permit crankpin 56 or 51 from piston set 5| to pass and to be engaged with one connecting member 6| or 62 as will be described. Each slot is elongated to permit the requisite degree of oscillatory motion to occur between the several piston sets.

To support further each of piston sets 2|, each wall 28 is provided with a bearing 3| to receive central bearing 65 on crankshaft 66.

In addition to the piston sets 2| so far described, a third piston set is provided and is indicated generally at 5|. This includes an annular central portion 52 which completes the piston channel defined by walls 23 and the central stator portion. The set 5| has four vane pistons 53 extending radially therefrom. This set is movable between the walls provided by piston sets 2| and within the annulus provided by the interior of stator central section l2. Each of the vane pistons on piston sets 2| includes sealing means generally indicated at 50 on the inner and the outer end of each vane. On piston set 5|, the sealing means is provided only at the outer end of each piston vane.

Each of piston sets 2| includes an annular ring 42 formed on one face thereof. Each end bell on the stator is formed to receive the periphery of a piston set wall while the central portion of the stator receives each ring 42 and so provides a seal for the piston channel formed between the piston set walls. Any fluid leaking past the piston set wall between the ring 42, the wall and the stator, passes into a space between the piston set and the adjacent interior surface of each end ates-ass bell I3. To assist in maintaining fluid pressure in this region, labyrinth seals are provided as indicated at 46 in the bearing support 33. Each labyrinth is provided by forming a plurality of circular grooves and providing like annular projections on the immediately adjacent surface, the two interengaging to provide a labyrinth seal. By bleeding fluid under pressure in the piston channel into this space, the pressure on opposite sides of the movable walls .can be equalized and the Walls sealed without the necessity of close tolerances between the several parts.

As appears in Figure 1, the central piston set 5| also includes two crankpins 56 and 51 placed 180 apart and extending through suitable slots 35 in wall 28 of each of piston sets 2| for engagement with a crosshead bearing .68 in each of the presently described connecting members 6| and 62.

A labyrinth seal 44 is provided between each piston set 2| and the third piston set to prevent fluid leakage from the piston channel into the central or crankshaft section of the device. This section is normally vented to the atmosphere and is maintained partially filled with a fluid lubricant to lubricate the several working parts.

The piston sets 2| and 5| rotate together as a unit. In addition, they have a limited rotary movement relative to each other, each set alternately accelerating and decelerating so that the rate of travel of alternate sets of pistons varies in such a way that the distance between adjacent sets of piston vanes changes from a maximum to a minimum during compression or scavenging of a charge and from a minimum to a maximum during the intake or power stroke as when the device is used as an internal combustion engine.

In accordance with the present invention, means are provided to ensure that corresponding variations in distance between adjacent pistons always occur cyclically and at the same point about the periphery of the stator. These means include a crankshaft 66 having crankpins 63 and 64 spaced 180 apart and on opposite sides of a central bearing 65 mounted in piston sets 2|. These means also include identical connecting members 6| and 62 mounted respectively upon opposite crankpins 63 and 64, As appears in Figure 1, each of the connecting members is mounted in the space between wall 28 on each piston set 2| and its bearing support 33. By making each piston set 2| and its bearing support member 33 in two separate parts, I am able to insert the connecting members and at the same time provide adequate bearing support for each of the piston sets 2|. Each of the connecting members includes three slots 61. In each slot is mounted a crosshead bearing 68 which in turn receives one of the crankpins 26 or 21 on one of the piston sets 2| or one of the crankpins 56 or 61 on the central piston set.

To control rotation of the connecting members and the several elements associated with them, and to ensure rotation of these in a cyclic manner, an integral spur gear 8| is formed at one end of each connecting member and-each spur gear is meshed with one of ring gears 82 on each ring gear member 39. To enable the device to be assembled in a simple manner, and to eliminate any unbalance during its rotations, counterweights 85 are provided on each crankshaft extension 83, the latter being joined by pins 84 to ends of the crankshaft crankpins. Bearing 86 in each cap 81 supports the shaft por- 6 tion 83 on each'throw, the caps being positioned on each end bell by studs 88.

The device described is readily utilized as an internal combustion engine, power being taken off from either shaft portion 83. In this case,- as appears in Figure 6, a suitable fuel charge is supplied and is admitted to intakes 9| provided on diametrically opposite sides of the stator oasing. A sparkplug or other firing means is provided at'each of points 92 on the casing, the two being again diametrically opposed and spaced approximately from each intake. The products are scavenged and exhausted after firing through exhaust ports 93. The device as described is suited to the Otto cycle of operation. It will be obvious to those skilled in the art that it can be adapted to other cycles as the Diesel cycle. 7

The device operates cyclically, the several piston sets rotating in the stator casing and alternately accelerating and decelerating whereby, in effect, the piston sets oscillate with respect to one another. In the device described, with three piston sets, each including four vanes, four charges will be drawn into the engine, four charges compressed, four charges fired and four charges scavenged for each revolution of the crankshaft, the charges being divided into two parts which are drawn in, compressed, fired, and scavenged on opposite sides of the piston channel. Each charge is drawn in on one side of the stator and exhausted at a point approximately removed from :the point of intake. Since each charge is divided into two parts, any pressure found at a given point in the piston channel will be duplicated in the piston channel at a. point away so that all loads on piston bearings resulting from fluid pressures are balanced out. In addition, the rotation of each of the piston members is mechanically controlled from two points 180 apart so that the greater part of the loads on the-piston bearings resulting from mechanical torque conversion is also balanced out. It should also be observed that while the crankshaft rotates three revolutions with respect to the stator in a given direction, the connecting members and sets of pistons will only make one revolution'with respect to the stator and that in a direction opposite to the direction of rotation of the crankshaft.

While I have specifically discussed a rotary displacement device including three piston sets, it will be obvious to those skilled in the art that any desired plural number of piston sets can be included. In addition, while my discussion has been limited to a structure in which each piston set includes four piston vanes, it should be obvious that any plurality of vanes can be employed, four being chosen purely for purposes of illustration.

In the form of the device shown in Figures '7 and 8 I have illustrated a combined internal combustion engine and fluid compressor including an explosive charge device as carburetor 15, inlet port 9|, sparkplug port 92, sparkplug 95 and exhaust port 93 on one side of the device. On the other side of the device I have provided an air or other fluid inlet ||I| diametrically opposite to the inlet port 9|. The gas admitted is compressed between one piston and the immediately adjacent piston, the compressed gas being released through port I62, preferably against the pressure of a suitable spring loaded valve indicated at I93. The gas is removed through line I04 into a suitable container I06 which is 7. useful to damp out pulsations in the rate of fluid delivery. From this container the gas can be withdrawn for use as desired. Referring particularly to Figure 7, I have shown a valve I01 as controlling release of the gas into a line I08 leading to a gas motor diagrammatically illustrated at 109, or other means for utilizing the fluid. If maximum utilization of fuel supplied to the device is desired, conduit III is preferably interposed between exhaust port 93 and a heat exchange indicated by numeral H2 through which the exhaust gases pass from the engine to heat the gas flowing through line I08 to the motor I09. In place of motor I09, the gas stream can be used in any other form of device for utilizing the compressed gas. For example, if the gas is air, the stream can be released to mix with a fuel and burn in a jet device.

Referring again to Figure 7, that portion of the fluid which is not released against the pressure of spring loaded valve 103 is carried on for release through exhaust ports I M, the resulting expansion of the fluid serving to return to the pistons any stored up energy in the fluid and, in addition, to cool the device prior to admission of the fuel charge and so remove heat from the device whereby the operating efficiency is improved.

I claim:

1. In an apparatus of the character described, a stator, at least three piston sets rotatably mounted in said stator as a unit and having a limited rotation with respect to one another, one of said piston sets including a central annular portion concentric with at least a portion of said stator and defining with said portion an annular piston channel, two other piston sets each having a wall closing a side of said annular piston channel and defining a fluid pressure chamber with said stator on that side of said wall opposite to said channel, a crankshaft rotatably mounted in said stator, a connecting member rotatably mounted on said crankshaft, coupling means between each piston set and said connecting member, and means for controlling rotation of said connecting member on said crankshaft.

2. In an apparatus of the character described, a stator having a plurality of ports for admitting afluid to a piston channel and a plurality of ports for releasing fiuid from said piston channel, at least three piston sets rotatably mounted in said stator as a unit and having a limited 5 rotation with respect to one another, one of said piston sets including a central annular portion concentric with at least a portion of said stator and defining with said portion an annular piston channel, two other piston sets each having a 1 wall closing a side of said annular piston channel and .defining a fluid pressure chamber with said stator on that side of said wall opposite to said channel, a crankshaft rotatably mounted in said stator, a connecting member rotatably mounted on said crankshaft, coupling means between each piston set and said connecting member, and means for controlling rotation of said connecting member on said crankshaft.

CHARLES BANCROFT.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,189,376 Miller July 4, 1916 1,303,255 Carter May 13, 1919 1,329,625 Noble Feb. 3, 1920 1,370,548 Neebe Mar. 8, 1921 1,732,995 'I'schudi Oct. 22, 1929 1,874,308 Kolko Aug. 30, 1932 1,889,508 Zens Nov. 29, 1932 1,920,201 Kolko Aug. 1, 1933 1,946,136 Farley Feb. 6, 1934 2,020,089 Weed Nov. 5, 1935 2,132,596 Bancroft Oct. 11, 1938 2,222,133 Wolstenholme Nov. 19, 1940 2,228,193 Bancroft Jan. 7, 1941 40 2,270,493 Bancroft Jan. 20, 1942 2,413,589 Snyder Dec. 31, 1946 2,453,271 Sales Nov. 9, 1948 FOREIGN PATENTS Number Country Date 419,123 Great Britain Nov. 6, 1934 458,969 France Oct. 23, 1913 467,924

France June 24, 1914 Certificate of Correction Patent No. 2,544,480 March 6, 1951 CHARLES BANCROFT It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows:

Column 5, line 61, for the numeral 67 read 5? column 8, list of references cited, under the heading UNITED STATES PATENTS add the following:

2,284,186 Wolstenholme May 96, 1.942

and that the said Letters Patent should be read as corrected above, so that the same may conform to the record of the case in the Patent Ofiioe.

Signed and sealed this 17th day of July, A. D. 1951.

ERNEST F. KLINGE,

Assistant Oommissz'oner of Patents. 

